Generally, a contact-type reading apparatus comprises a contact glass, a linear array of light-emitting diodes (LEDs) that serves as an illumination source which sends rays of light through a light guide that focuses the light onto the surface of the document to be read. The LEDs and the light guide span the entire reading length reading apparatus. The illuminated portion of the document is reflected and focussed by an optic fiber lens array onto an optical sensor array. The optical sensor array consists of one or more solid state devices comprising multiple individual photo cells in a linear array, which convert the image focussed onto them into electrical signals, producing a digital image which can be stored in an internal memory for future use.
This kind of contact-type reading apparatus is not easily adaptable for use in a portable reading apparatus. The LEDs pose two problems. First, to evenly illuminate the document to be read, the LEDs must span the entire length of the reading apparatus. However, this arrangement is too cumbersome for a portable device. Second, the LEDs require considerable current to function, thus a substantial amount of battery power would be wasted on merely illuminating the LEDs, in a portable apparatus.
Another kind of contact-type scanner comprises a light pipe, or wave-guide, instead of a linear array of LEDs. The wave-guide includes a clear, glass or plastic pipe with an LED located at either end. The inside bottom surface of the pipe is painted white and as the LEDs discharge light through the pipe, the light is reflected by the white paint and the light is dispersed evenly in order to illuminate the document as it passes over the substrate. Then, the illuminated portion of the document is reflected and focussed by a lens array onto an optical sensor array.
It is an object of the present invention to disclose a hand-held scanner comprising contact image sensor scanning technology, and a waveguide formed in a substrate. The scanner is extremely lightweight and narrow in design because the bulkiness of a linear array of LEDs is eliminated, and is replaced with a waveguide that is formed in a substrate.
The length of the scanner is approximately equal to the width of a standard sheet of paper. The reading mechanisms are the long length of the unit such that the reading method comprises pressing the unit across a document to be read and manually moving the module in the direction desired.
The waveguide comprises a light pipe, which light pipe includes light sources disposed at either end, and a reflective cladding deposited on an inside lateral surface. The light sources emanate a plurality of light rays through the light pipe and which propagate in the light pipe until striking an area of the reflective layer. The light rays are directed away from the reflective layer and onto the scan line of the document. Light from the illuminated scan line is reflected back through the waveguide array and onto the optical lens array. The optical lens array then focuses the light onto an optical sensor array. The optical sensor array converts the image received into electrical signals to produce a digital image to be stored in an internal memory.
In another embodiment, light of the illuminated scan line is reflected back through the waveguide formed in a substrate and strikes a mirrored surface. The mirrored surface is positioned at an angle relative to the waveguide and directs the light from an illuminated scan line through an optical lens array. The optical lens array focuses the light onto another mirrored surface that is mounted at an angle. The mirrored surface reflects the light onto an optical sensor array, which convert the image into a digital image, to be stored in an internal memory.